October 10, 2012

Researchers Say X-Rays From Dead Stars May Guide Future Spacecraft

The European Space Agency (ESA) has commissioned a research team, including scientists from the National Physical Laboratory (NPL) and the University of Leicester, to investigate the possibility of using dead stars to navigate in deep space. If it is found to be feasible, this technique could revolutionize the way spacecraft navigate in the outer Solar System and beyond.

Currently, spacecraft navigation relies on radio transmissions between the craft and a network of ground-stations on Earth. The craft has to wait for instruction from Earth for guidance, which can take from hours to days depending on how far out the spacecraft is. The time delay affects the craft's ability to react rapidly, and the infrastructure on the ground is expensive and difficult to maintain because of the large size of the radio antennas.

The research team is exploring the use of the X-rays from pulsars to allow spacecraft to navigate autonomously. Highly compact, pulsars are rapidly rotating neutron stars that emit intense eletromagnetic radiation. The radiation is observed as pulses, similar to the rotating light of a lighthouse or an airport beacon. Because the pulses can be highly regular, they are suitable sources for navigation using a technique similar to GPS.

"Using on-board X-ray detectors, spacecraft could measure the times of pulses received from pulsars to determine the position and motion of the craft. The University of Leicester will use their experience in X-ray astronomy to come-up with potential designs of the device and NPL will develop timing and navigation algorithms to determine the potential accuracy of this technique. Funding received from ESA will allow us to investigate the feasibility of using these dead stars and the potential navigation performance that could be derived," explained Setnam Shemar, who is leading the project on behalf of NPL's Time and Frequency team.

Only a limited number of spacecraft can be supported by traditional forms of ground-based space navigation, as only one set of measurements can be processed at any given time. This new technique could potentially allow a greater number of complex space missions to operate simultaneously in deep space.

ESA's technical strategy for the future will be advised by the results of this investigation. If the technique is successful, pulsar navigation could reduce the costs and limitations associated with ground-based space navigation in the long-term. This, in turn, might eventually enable us to navigate beyond the outer Solar System.